| A reverse DNA strand exchange mediated by recA protein and exonuclease I. The generation of apparent DNA strand breaks by recA protein is explained. | |
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MedLine Citation:
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PMID: 8325876 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The combined action of exonuclease I and recA protein leads to a kind of reverse DNA strand exchange in which joint molecules formed on the "wrong" or distal end of a linear duplex in the presence of ATP are stabilized by exonuclease I degradation of the displaced (+) strand. Continued pairing and degradation of the displaced strand leads to strand exchange that appears to progress with a polarity opposite that of the normal recA protein promoted reaction (i.e. 3'-5' with respect to the (+) strand). However, in contrast to the normal 5'-3' strand exchange, the displaced strand is completely degraded in the process. When the linear duplex DNA substrate has a heterologous region at the 5' (proximal) end, the major product (described in a previous study (Bedale, W. A., Inman, R. B., and Cox, M. M. (1991) J. Biol. Chem. 266, 6499-6510)) is a circular duplex DNA molecule with a double-stranded tail whose length corresponds closely to the heterologous segment of the substrate. The origin of this product is here shown to be the result of the exonuclease activity of exonuclease I (either added exogenously or present as a trace contaminant of recA protein or SSB protein preparations), as opposed to endonucleolytic or mechanical breakage. The levels of exonuclease I required to generate these products are sufficiently low that they are undetected by assays for exonuclease contamination in recA protein preparations. These results demonstrate that the interplay of recA protein with other enzymes can have a profound effect on both the mechanism and outcome of recA protein-promoted DNA strand exchange. They also demonstrate that the (+) strand of the duplex DNA substrate is at least transiently displaced in recA protein-mediated pairing even when joint molecules are limited to the distal end. |
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Authors:
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W A Bedale; R B Inman; M M Cox |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: The Journal of biological chemistry Volume: 268 ISSN: 0021-9258 ISO Abbreviation: J. Biol. Chem. Publication Date: 1993 Jul |
Date Detail:
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Created Date: 1993-08-12 Completed Date: 1993-08-12 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 2985121R Medline TA: J Biol Chem Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 15004-16 Citation Subset: IM |
Affiliation:
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Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin, Madison 53706. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Bacteriophage M13
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genetics DNA / metabolism*, ultrastructure Escherichia coli / genetics Exodeoxyribonucleases / metabolism* Microscopy, Electron Rec A Recombinases / metabolism* Recombination, Genetic |
| Grant Support | |
ID/Acronym/Agency:
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GM14711/GM/NIGMS NIH HHS; GM32335/GM/NIGMS NIH HHS; T32-GM07215/GM/NIGMS NIH HHS |
| Chemical | |
Reg. No./Substance:
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9007-49-2/DNA; EC 2.7.7.-/Rec A Recombinases; EC 3.1.-/Exodeoxyribonucleases; EC 3.1.11.1/exodeoxyribonuclease I |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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